Definition

The process of applying a new law or rule to actions or events that happened in the past before the law was created.

Example

The retroactivity of the new tax law surprised many citizens who thought their previous actions were unaffected.

Conversation

Did you hear about the new law they just passed?

Yeah, it's surprising how it has retroactivity for events from last year.

I wonder how that will affect people who were impacted before the law.

It could really change things, especially for those who thought they were safe.

Synonyms & Antonyms

Root Explanation

Retroactivity → It is formed from "retro-" (meaning backward) and "activus" (from Latin, meaning active). The word refers to the quality of being effective from a date in the past, hence acting backward in time.

Memory Tip

Think of 'backward' ('retro-') actions that are 'active' ('activus') — this helps you remember that retroactivity means something that takes effect from the past.

Visually Confused Words